Furnace grate



June 21 1927 E. B. PRIEBE ET AL FURNACE GRATE Filed June 25. 1921 2 Sheets-Sheet l jvoa'wl'o J www ma fa QowNw@ a Cown.

Patented June 21, 1927."

UNITED STATES PATENT OFFICE.

ERNEST B. PRIEBE, 0F IN'WOOD, NEW YORK, .LND DANIEL P. m3, 0l' PROVIDENCE, RHODE ISLAND; SAD) m3 ASSIGNOB 0I' HIS UNDIVIDED ONE-HALF INTEREST T0 WARREN C. BRAKE, OF INWOQD, NEW YORK.

IUENAGE GBATE.

Application med June 25. 1921. Serial lo. 480,894.

This invention is a novel furnacev grate adapted for use in connection with automatic stokers and being herein illustrated in connection with an underfeed stoker forl a boiler furnace. The general objects of the present invention are to afford a furnace grate and Stoker of greater eliciency in operation and superior strength and durability in construction. A particular object is tominimize the diliiculty of the sifting of ashes through the grate into the wind box, which has been quite pronounced in certain types of stokers. Another object is to improve the operation and eliiciency of the furnace by perfecting the manner and meansY of air distribution. Another specie object is to afford a novel and advantageous system of twyers for a furnace grate. Other and further advantages of the present invention will be made to appear in the hereinafter following description of one form of embodiment thereof or will be apparent to those skilled in the art.

To the accomplishment of the objects and advantages mentioned the present invention consists in the novel furnace grate and stoker herein described and illustrated and the novel `features of arrangement, combination, construction and operation thereof.

In the accompanying drawings Fig. 1 is a longitudinal section of a multiple retort furnace and stoker embodying the principles of the present invention.

Fig. 2 is atransverse section taken on the vertical line *22 of Fig. 1.

Fig. 3 is a perspectlve view on an enlarged scale showing in detail the construction of the extension grate.

Fig. 4 is a transverse section taken on the inclined line 4-4 'of Fig. 1.

Although the invention ht be applied to furnaces and grates of 'lferent kinds and types it is herein shown applied to the multiple retort type illustrated in'prior patent of Priebe 1,360,250 of November 23, 1920. Certain illustrated devices are not herein claimed to be novel, being well known constructions not requiring detail description, for example the coal infeeding means as shown in Fig. 1 being similar to that shown in said prior Priebe patent.

Referring to the details of the herein illustrated embodiment of the present invention, the combustion chamber of the furnace is shown as bounded by the usual wall 7 at the front, bridge wall 8 at the rear and side walls 9, 9.

The illustrated structure possesses the advantage of minimizing sifting into the wind box, also a very advantageous and thorough air distribution into all of the fuel bed overlying the grates, this greatly improving the efliciency of combustion. -In addition to these advantages the feature of the present invention involving a certain amount of looseness and play between the different grate bars prevents any damage from expansion and contractionV of the metal; the structure has an elasticity or self yielding quality which takes care of the difficulties frequently involved in the expansion of the metal. Another and very important advantage of this invention is the protection 4of the gratebars by maintaining them relatively cool. This is due to the mode of air travel, which passes horizontally through the spaces between the inclined grate bars and therefore has an extended length ot travel in contact with the metal. The coolin effect is therefore applied more eiciently anl completely than in a different arrangement, and the heat which is produced at the'outer surface of the grate bars is the more readily conveyed away and dissipated, thus the burning away and destruction ofthe metal of the grate bars.

The 'general 'structure of furnace and stoker is similar to that disclosed in the prior Priebepatent, above mentioned, and therefore reference to many details will be omitted. The front wall 7, bridge wall 8 and side walls may be as shown. The fuel bed 15 is supplied from an exterior coal hopper 16 from into the furnace by a ram 17 operated and which the fuel is underfed 9:

made up controlled by mechanism 23. The fuel passes into a series of longitudinal retorts 25, and is thrust upwardly forming .a bed overlying the entire grate, and eventually passing downwardly to the dumping grate 26, which periodically discharges' the refuse into the ash pit .27. The retorts are in the form of inclined troughsextending downwardly toward the rear, and each retort may contain one or more distributing rams or pushers 91, maintaining the fuel in gradual progress toward the rear. The retorts are formed between a series of twyer boxes 92 above each of which is a bank of twyer members o'r blocks 93, shown the same as in the prior Priebe patent, and overlying theseupstanding twyer members are a series of overlapping cap pieces 94, which complete the twyer construction between the retorts.l The main air duct 95 leads to the compartmented wind box 96 which supplies air both to the twyer boxes 92 and to the terminal grate section 97, which may be termed an extension grate as it follows after the main rate and supports the fuel which has passed beyond the retorts on its way to the dumping grate.

The present invention is shown applied herein, not to the main grates, but to these extension rates 97. The extension grate is of a series of groups of grate members or bars, and the groups are relatively reciproeated during combustion, the upper side of the movable portions sliding beneath a coal plate 98 which in turn is located directly beneath the lower ends of the system "of twyer members 93 and cap pieces 94,

that is, at the rear or discharge ends of the retorts, from which point the extension ate members extend in vthe same longitu inal` direction as the retorts, toward the dump grate 4and bridge wall. The combustion in this part of the furnace, between the main grate and the dumping grate, is of substantial importance and the present improvement adds material efficiency thereto.

The grate bars 7 5a in one group and the similar grate bars 75b in an adjacent group are generally similar. Each is shown as having the rightward ribs 83 and leftward ribs 84, giving recesses and affording the interengaging structure, the iit being sufiiciently loose to give horizontal air passages of substantial length from the underside of the slanting bars to ,the upper side thereof. Since all of the bars 7 5'* of one group move in unison they are identical and the upper ends of all of them are flush and located directly beneath the coal plate 98. All of the grate bars of each oup are connected permanently together y-a rod 99 which also connects all of them to the upstanding brackets or flanges 100 of an underlying support 101 so that each two adjacent groups while interengaged with each other through the ribs 83 and 84 are independent in regard to-longitudinal reciprocation. The Stoker may be operated so that alternate groups re. main stationary while those between are reciprocated, but we prefer, that as one group 7 5a moves forwardly the adjacent group 7 5" moves rearwardly thus giving alternate opposite reciprocating motions, which assist in the advance of the fuel bed as it passes over the extension grates on the way to the dumping grate. Each of the supports 101 is shown as having downward flanges 102 by which it is slidingly fitted upon the underlying guiding means or stationary members 103 of the furnace structure. A suitable reciprocating means consists of a rock shaft 104 connected by arm 104 and link 104b with the lugs 102, and anactuating arm 105 moved forwardly and rearwardly by a connecting rod 106 extending to an oscillating lever 107 at the exterior front of the 4machine, which is pivoted at 108 and receives its actuation from the operating -mechanism 23.

The air of combustion passes from the wind box 96 into the auxiliary wind b ox'109 beneath theA grate bars 75 and 75h, the air passing through a damper 110, controlled'by an exterior handle 111. From the wind box 109 the air .enters the fuel bed between the respective grate bars of the extension grate.

yIt will thus be seen that we have described a furnace grate embodying the rinciples and attaining the objects and a vantages of the present invention. Since many matters of arrangement, combination, d si n and detail may be variously modified wlthout departing from the principles involved,'it is not intended to limit the invention to such matters except in so far as specified in the appended claims.

What is claimed is:

1. In a furnace grate having a plurality of parallel inclined fuel retorts discharging longitudinally, the combination therewit of an extension grate receivin burning -fuel from the retorts and conductlng it longitudnally towards a rear dumping point, consisting of numerous downwardly inclined longitudinal grate bars, with their upperl .2. In a furnace grate having a plurality of parallel inclined fuel retorts dischar ing longitudinally, the combination therewit of an extension grate receiving burning fuel from the retorts and conducting it longitudinally towards a rear dumping point, consisting of numerous downwardly inclined and ing arranged in downwardly trending loosely assembled solid cast grate bars, each -stepped formation. having at its two sides staggered side ribs:v In testimony whereof, we have aiiixed our 10 projecting into the spaces between the ribs signatures hereto.

of adjacent grate bars to afford numerous narrow air passages into the fuel bed,l the ERNEST B. PRIEBE.

upper surfaces of the bars and said ribs be- A v DANIEL P. MINER. 

